i am working on a 93 4x4 at work and the tranny will not go into over drive inless floored hard and then it drops in suddenly, i played with the tps sensor and that worked a bit but then on there way back from town they said it started it again, it will not go into over drive inless it's revved out really hard then slams into over drive, what could be causing this? it shifts 1,2 fine but around 75-80kmh it revvs hard and wont shift untill you really berry it. whats happing here?
thanks
Gregg

 

Can't help much with your problem, however if it only shifts 1-2-3 it ain't no o'drive! O'drive trannies have 4 speeds, Torqueflite 727 has 3.

 

I'm having the exact same problem with my '92, it just doesn't want to go into OD sometimes and sometimes it will jump in/out of OD as I'm cruising along at around 80 km/h.

 

The PCM recieves a signal from the speed sensor and the tps. The tps should read 1 volt at idle and have a smooth increase as the throttle is moved to full fuel. The center wire is the output of the tps. It can be probed by inserting the test lead down along the wire into the plug using a digital volt meter. The ground lead can go to the negative terminal of the battery.
the speed sensor also drives the speedometer. If the speedometer is working then the problem most likely is the TPS.
The PCM actually switches the ground to a solenoid in the valve body. The wire from the PCM plugs in on the driver's side near the TV cable and linkage. Be careful that you don't break the socket. It is a real pain to change. It is a hard wired connection to the O/D solenoid. It requires pulling the valve body to replace it.

 

It sounds like the TPS is flaky. I would replace it.

 

Whenever my truck does that I change my fuel filter and it goes right back to normal.

 

Mine had a similar problem. The mechanical kickdown linkage would stick and cause the problem. Look under the hood and find the elongated slot in the throttle cable linkage where it connects, near the pump, to the tranny cable. Lube that and make sure it is not binding.

Also, after almost burning my tranny up on a very long hard pull it would not shift right. A fluid change helped a lot. The final thing is the PRNDL adjustment. Make sure the shifter is in the right spot. You can do this by driving at a speed where it should shift but doesn't and playing with the shifter to see if moving it a bit caues the correct shift.

John

 

Thanks for the info...I'll change the tranny fluid and the fuel filter and lube the kickdown.